It's a really fun learning experience but hard to make it profitable on a small scale. I've been selling live copepod cultures for a while and while I do occasionally sell some, the local demand isn't high enough to make it a reliable source of income.
In order to make it worthwhile, you might be able to sell it in bulk for cheaper than the going rate.
What ingredients and nutrient profiles are you considering that would make yours stand out from brand name foods?
Some common but effective ingredients:
Spirulina (home grown or powder)
Amino acids
Garlic
Oyster puree
Mysis shrimp